Quote:
Originally Posted by rca2000
But WHY--won't filamants in air glow?
i HAVE seen this before--but don't fully understand it.
|
Because air conducts heat away from the heater much better than vacuum... that is likely why the neck is getting very warm.
Quote:
Originally Posted by WISCOJIM
Filaments in air will usually burn out.
The neck getting warm sounds like something inside the tube is shorted out.
|
IF the full 6.3 volts is applied... I think that the cold resistance of the heater is so low that the tester voltage sags down to a lower voltage.
jr